One aspect of the invention relates to a microphone comprising a cylindrical transducer housing with a lateral axis and having a centre section and two end sections, the centre section having non-parallel, elliptical end faces oriented mirror-symmetrically with respect to a plane perpendicular to the lateral axis, the end sections having inner end faces confronting and parallel to respective ones of the centre section end faces, and microphone transducers mounted to receive sound from beween the respective end sections and the centre section.
Another aspect of the invention relates to a loudspeaker comprising:
a cylindrical, hollow housing with a lateral axis and having a centre section and two end sections, the centre section having non-parallel end faces oriented mirror-symmetrically with respect to a plane perpendicular to the axis, the end sections having inner end faces confronting and parallel to respective ones of the centre section end faces; and
four speaker transducers mounted in the housing, with two centre transducers in the centre section radiating towards respective ones of the end sections, and one end transducer in each of the end sections radiating towards the centre section, each transducer being sealed to the housing.
A microphone and a loudspeaker of these types are disclosed in EP-A-0 256 688 (CA-A-1 282 711, granted 9 Apr. 1991 to Raymond Wehner, the applicant in this application).
CA-A-1 060 350, granted 14 Aug. 1979, and EP-A-0 256 688, describe microphone and loudspeaker systems that are directed to the recording and open-air reproduction of sound fields so that the reproduced sound field includes the directional and range information from the originally recorded field for detection by the human hearing system. Microphones in these systems are intended to be analogs of the human hearing system, detecting the range and direction sound information that would be detected by the human hearing system. The loudspeaker aspect of the system exemplifies the Hamilton-Jacobi theory of wave movement.
The loudspeakers are intended to invert the detection process and to generate a sound field containing the direction and range information originally available.